An electronic zigzag sewing machine such as a lock-stitch sewing machine conventionally offers standard equipment of functions such as needle swinging, sewing speed control, slow start, and display settings; where the needle swinging function swings a sewing needle by swinging a needle bar, the sewing speed control function allows change in sewing speed, the slow start function decelerates the sewing speed at sewing start, and the display settings allows modification of settings such as size of characters displayed in messages, and the like, on a liquid crystal display.
For instance, the pattern sewing machine described in JP H10-286384 A (pages 5 to 7, FIGS. 7 and 8), keeps track of count of user operation of each function key provided for selection of a sewing pattern in the pattern selection process. The count of user operation is represented by operation count I which is incremented every time the corresponding function key is operated. Technical maturity of the user is evaluated based on the count of operation count I of the function keys, and a maturity level classified into levels of “1 to 3” is assigned to the user based on the evaluation. Depending on the maturity level assigned to the user, either one of icons “M1 to M3” and a predetermined number of sewable patterns both preset to each sewing level “1 to 3” are both displayed to the user. Similarly, in an edit process control, a maturity level of “1 to 3” is determined based on the operation count I of the function key, and either one of the icons “M1 to M3” and a predetermined number of sewable patterns both preset to each editing level “1 to 3” are both displayed to the user.
In the pattern sewing machine described in the above publication, user technical maturity is detected (determined) based on the accumulated operation count I of the function keys after the date of purchase of the sewing machine. Hence, if the sewing machine is purchased by a young girl who is inexperienced in operating a sewing machine and the sewing machine is being shared by her family, in this case, her mother and her grandmother, the operation count I will not show much increase after the date of purchase while the sewing machine is mainly used by the young girl. Under such state, when her mother and grandmother, being experienced in sewing machine operation, use the sewing machine, they are only allowed to sew small number of sewing patterns and use only simple function keys, being unreasonably constrained by the limitations applied to the young girl who is an inexperienced user.
Contrastingly, after substantial lapse of time after the date of purchase of the sewing machine where operation count I of the function keys have substantially increased and maturity level has grown substantially high, and the young girl's younger sister, for example, who is even more inexperienced in sewing machine operation, uses the sewing machine under such state, she may hesitate to use the sewing machine or feel uncomfortable in operating the sewing machine since she is forced to select a pattern requiring high sewing skills from the very beginning and may encounter display of function keys for use by experienced users which is not for use by beginners.